This invention relates to telephone systems and more particularly to apparatus for locating faults in a carrier subscriber telephone system.
A typical carrier subscriber telephone system comprises carrier equipment that is normally collocated with central office telephone equipment at an office facility, a plurality of repeaters, and carrier subscriber equipment that is located at different subscriber stations or which is collocated at a cluster subscriber station. The repeaters are connected in series between the central office and station carrier equipment by means of associated cable sections which may be lengths of coaxial cable or twisted pair telephone cable.
In a computer controlled ten channel cluster carrier subscriber telephone system, carrier equipment at the central office location typically comprises apparatus for transmitting high frequency signals (e.g., channel frequencies between 92 and 148 kHz together with low and high frequency out-of-band pilot signals such as 88 kHz and 160 kHz), apparatus for receiving low frequency signals (e.g., channel frequencies between 12 kHz and 68 kHz), and a computer means for controlling the operation of the system. The repeaters operate to periodically increase the signal to noise ratio and integrity of carrier signals. All of the repeaters are preferably identical and comprise high and low frequency sections for passing office location signals to subscriber stations, and vice/versa. The high frequency repeater section essentially comprises a pair of 84-184 kHz high frequency filters flanking amplifier circuitry that passes signals only in the direction of the subscriber stations. Conversely, the low frequency repeater section comprises a pair of 8-72 kHz, for example, low frequency filters flanking amplifier circuitry that passes signals only in the direction of the office. Each repeater also comprises a microprocessor or microcomputer or other type of computer means that is responsive to control signals from the office computer for controlling the operation and/or characteristics of the repeater, e.g. the slope of the filter characteristics and the gain of the amplifiers.
From time to time, communication between the office and the cluster station may be faulty due to an entire or partial failure of one of the components in the repeater, damage to a cable, improper power supply voltage, or some other malfunction in the system. In order to avoid undue interruption of service for any of the above reasons, it is desirable to check the integrity and operation of the carrier subscriber system periodically for faults. It is also desirable to make such a check while the system is being operated in a normal communication mode. If a fault is found to exist, it is further desired to determine the location of the fault so that repair and/or preventative maintainence can be judiciously assigned and readily facilitated.
An object of this invention is the provision of improved apparatus for testing components of a carrier subscriber communication system.
Another object is the provision of improved apparatus for identifying and/or indicating the location of faults in components of carrier subscriber equipment.
Another object is the provision of apparatus for detecting and/or locating faults in a carrier subscriber communication system which utilizes existing system components, which requires few additional components, and which may be performed without interrupting normal use of the system.